Item Summary

In an attempt to better understand how evolution from oviparity to viviparity might alter energy demand and allocation, energy budgets were determined for adult females of four species of cockroaches, the oviparous Supella longipalpa, the facultative ovoviviparous Blattella germanica, the ovoviviparous Pycnoscelus indicus and the viviparous Diploptera punctata. Food consumption and feces production in all species were greatest during the early part of a reproductive cycle, immediately after oviposition for S. longipalpa and immediately after offspring hatching in B. germanica, P. indicus and D. punctata. Respiration in three of the four species (all except D. punctata, where respiration was constant throughout the cycle) closely paralleled food consumption with respiration highest early in the reproductive cycle. Ovoviviparity in cockroaches was characterized by the addition (to the oviparous condition) of a quiescent postoviposition gestation period, during which the female ate and respired little in comparison to preoviposition rates. Viviparity in D. punctata was characterized by a more constant rate of consumption (although still fastest in the first third of the reproductive cycle) and a constant rate of respiration. While there were significant differences in the temporal patterns and rates of energy acquisition and allocation associated with the different modes of reproduction, changes in the relative proportions of energy allocated to competing demands such as respiration, weight gain and reproductive products were slight. Multiple estimates of reproductive effort (RE), the proportion of an organism's energy budget devoted to reproduction, were calculated using seven indices based exclusively on energy budget parameters (allocation-based indices) and two mixed indices based on female body weight (soma-based indices). All but one of the allocation-based indices showed the same interspecific ranking of RE, S. longipalpa > P. indicus > B. germanica == D. punctata, while the interspecific ranking of the two soma-based indices differed from that of the allocation-based indices and from each other. Substituting ash-free dry weight or dry weight for energy equivalents reduced the absolute value of both allocation-based and soma-based RE Indices. Among allocation-based indices. those which contained more energy budget parameters yielded greater absolute RE estimates than less complicated indices. These results suggest that previous reports of agreement between allocation-based and soma-based RE estimates were probably coincidental.

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